#region Copyright & License

//
// Copyright 2001-2005 The Apache Software Foundation
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//

#endregion

using System;
using log4net.Core;
using log4net.Util;

namespace log4net.Appender {
  /// <summary>
  /// Buffers events and then forwards them to attached appenders.
  /// </summary>
  /// <remarks>
  /// <para>
  /// The events are buffered in this appender until conditions are
  /// met to allow the appender to deliver the events to the attached 
  /// appenders. See <see cref="BufferingAppenderSkeleton"/> for the
  /// conditions that cause the buffer to be sent.
  /// </para>
  /// <para>The forwarding appender can be used to specify different 
  /// thresholds and filters for the same appender at different locations 
  /// within the hierarchy.
  /// </para>
  /// </remarks>
  /// <author>Nicko Cadell</author>
  /// <author>Gert Driesen</author>
  public class BufferingForwardingAppender : BufferingAppenderSkeleton, IAppenderAttachable {
    #region Public Instance Constructors

    #endregion Public Instance Constructors

    #region Override implementation of AppenderSkeleton

    /// <summary>
    /// Closes the appender and releases resources.
    /// </summary>
    /// <remarks>
    /// <para>
    /// Releases any resources allocated within the appender such as file handles, 
    /// network connections, etc.
    /// </para>
    /// <para>
    /// It is a programming error to append to a closed appender.
    /// </para>
    /// </remarks>
    protected override void OnClose() {
      // Remove all the attached appenders
      lock (this) {
        // Delegate to base, which will flush buffers
        base.OnClose();

        if (m_appenderAttachedImpl != null)
          m_appenderAttachedImpl.RemoveAllAppenders();
      }
    }

    #endregion Override implementation of AppenderSkeleton

    #region Override implementation of BufferingAppenderSkeleton

    /// <summary>
    /// Send the events.
    /// </summary>
    /// <param name="events">The events that need to be send.</param>
    /// <remarks>
    /// <para>
    /// Forwards the events to the attached appenders.
    /// </para>
    /// </remarks>
    protected override void SendBuffer(LoggingEvent[] events) {
      // Pass the logging event on to the attached appenders
      if (m_appenderAttachedImpl != null)
        m_appenderAttachedImpl.AppendLoopOnAppenders(events);
    }

    #endregion Override implementation of BufferingAppenderSkeleton

    #region Implementation of IAppenderAttachable

    /// <summary>
    /// Adds an <see cref="IAppender" /> to the list of appenders of this
    /// instance.
    /// </summary>
    /// <param name="newAppender">The <see cref="IAppender" /> to add to this appender.</param>
    /// <remarks>
    /// <para>
    /// If the specified <see cref="IAppender" /> is already in the list of
    /// appenders, then it won't be added again.
    /// </para>
    /// </remarks>
    public virtual void AddAppender(IAppender newAppender) {
      if (newAppender == null)
        throw new ArgumentNullException("newAppender");
      lock (this) {
        if (m_appenderAttachedImpl == null)
          m_appenderAttachedImpl = new AppenderAttachedImpl();
        m_appenderAttachedImpl.AddAppender(newAppender);
      }
    }

    /// <summary>
    /// Gets the appenders contained in this appender as an 
    /// <see cref="System.Collections.ICollection"/>.
    /// </summary>
    /// <remarks>
    /// If no appenders can be found, then an <see cref="EmptyCollection"/> 
    /// is returned.
    /// </remarks>
    /// <returns>
    /// A collection of the appenders in this appender.
    /// </returns>
    public virtual AppenderCollection Appenders {
      get {
        lock (this) {
          if (m_appenderAttachedImpl == null)
            return AppenderCollection.EmptyCollection;
          else
            return m_appenderAttachedImpl.Appenders;
        }
      }
    }

    /// <summary>
    /// Looks for the appender with the specified name.
    /// </summary>
    /// <param name="name">The name of the appender to lookup.</param>
    /// <returns>
    /// The appender with the specified name, or <c>null</c>.
    /// </returns>
    /// <remarks>
    /// <para>
    /// Get the named appender attached to this buffering appender.
    /// </para>
    /// </remarks>
    public virtual IAppender GetAppender(string name) {
      lock (this) {
        if (m_appenderAttachedImpl == null || name == null)
          return null;

        return m_appenderAttachedImpl.GetAppender(name);
      }
    }

    /// <summary>
    /// Removes all previously added appenders from this appender.
    /// </summary>
    /// <remarks>
    /// <para>
    /// This is useful when re-reading configuration information.
    /// </para>
    /// </remarks>
    public virtual void RemoveAllAppenders() {
      lock (this) {
        if (m_appenderAttachedImpl != null) {
          m_appenderAttachedImpl.RemoveAllAppenders();
          m_appenderAttachedImpl = null;
        }
      }
    }

    /// <summary>
    /// Removes the specified appender from the list of appenders.
    /// </summary>
    /// <param name="appender">The appender to remove.</param>
    /// <returns>The appender removed from the list</returns>
    /// <remarks>
    /// The appender removed is not closed.
    /// If you are discarding the appender you must call
    /// <see cref="IAppender.Close"/> on the appender removed.
    /// </remarks>
    public virtual IAppender RemoveAppender(IAppender appender) {
      lock (this) {
        if (appender != null && m_appenderAttachedImpl != null)
          return m_appenderAttachedImpl.RemoveAppender(appender);
      }
      return null;
    }

    /// <summary>
    /// Removes the appender with the specified name from the list of appenders.
    /// </summary>
    /// <param name="name">The name of the appender to remove.</param>
    /// <returns>The appender removed from the list</returns>
    /// <remarks>
    /// The appender removed is not closed.
    /// If you are discarding the appender you must call
    /// <see cref="IAppender.Close"/> on the appender removed.
    /// </remarks>
    public virtual IAppender RemoveAppender(string name) {
      lock (this) {
        if (name != null && m_appenderAttachedImpl != null)
          return m_appenderAttachedImpl.RemoveAppender(name);
      }
      return null;
    }

    #endregion Implementation of IAppenderAttachable

    #region Private Instance Fields

    /// <summary>
    /// Implementation of the <see cref="IAppenderAttachable"/> interface
    /// </summary>
    AppenderAttachedImpl m_appenderAttachedImpl;

    #endregion Private Instance Fields
  }
}